TOC
Control Devices
LIMITER DIODES
DESCRIPTION
The GC4700 series diodes are specially processed PIN
diodes designed for use in passive or active limiters at
frequencies through Ku band.
Twelve categories of devices are offered for flexibility
in design of low (lower Vb, fastest turn-on time), me-
dium and high (highest Vb, slowest turn-on time)
power limiters.
APPLICATIONS
A diode limiter is a power-sensitive variable attenuator
that uses the non-linear properties of the diode to pro-
vide an impedance mismatch when sufficient amounts
of RF power are incident on the device. The output
power is reduced to a level that will not overdrive a re-
ceiver, burn out a mixer, etc. For varying input power
levels in excess of the diode鈥檚 threshold level, the limiter鈥檚
output power tends to remain constant.
A passive limiter is one in which the limiter diodes are
鈥渢urned on鈥?by the RF signal itself. An active limiter is one
in which the limiter diodes are 鈥渢urned on鈥?primarily by an
external bias current typically supplied by a Schottky de-
tector diode which senses the incident signal.
Since limiter diodes are not designed to dissipate large
amounts of power, the limiter must reflect or divert the
excess incident power back to the source or to another
load (i.e. via a circulator, hybrid coupler, etc.).
Limiter diodes may be used in wave guides, coax, mi-
crostrip, stripline or other media. Single or cascaded
devices may be used, depending on power levels.
DC BLOCK
位
4
COARSE
(HIGH
POWER)
LIMITER
DIODE
DC BLOCK
CLEAN UP
OUTPUT
(FAST)
LIMITER
DIODE
INPUT
DC
RETURN
BASIC TWO-DIODE LIMITER
CHIP ELECTRICAL PARAMETERS: T
A
= 25擄C
MODEL
NUMBER
V
B
MIN (VOLTS)
IR = 10碌A(chǔ)
C
JO
TYP
(pF)
C
J6
MAX
(pF)
TYPICAL
R
S
@10 mA
(Ohms)
TYPICAL
T
L
(nS)
TYPICAL
MAXIMUM
THERMAL
(擄C/W)
胃
P
1
2
(擄C/W)
RESISTANCE
GC4701
GC4702
GC4711
GC4712
GC4713
GC4721
GC4722
GC4723
GC4731
GC4732
GC4741
GC4742
20
20
45
45
45
120
120
120
15
15
30
30
0.20
0.50
0.20
0.50
0.70
0.20
0.60
0.80
0.12
0.20
0.12
0.20
0.15
0.30
0.15
0.30
0.50
0.15
0.30
0.50
0.10
0.15
0.10
0.15
1.5
1.2
1.5
1.2
1.0
1.5
1.0
0.5
2.0
1.5
2.0
1.5
5
10
10
15
20
50
50
100
5
5
7
7
20
12
15
10
6
1.2
0.5
0.3
30
20
20
15
100
80
80
60
40
40
20
15
120
80
100
70
1) Pulse length 1 microsecond.
2) As measure in style 30 package.
SEMICONDUCTOR OPERATION
75 T
echnology Drive 聲 Lowell, MA 01851 聲 T
el: 978-442-5600 聲 Fax: 978-937-3748
83
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